Conventionally desiccant air-conditioning systems that use desiccant rotors have been used as air conditioners for maintaining low humidity levels in cold storage warehouses, battery factories, and the like (See, for example, Japanese Unexamined Patent Application Publication 2006-308229 and Japanese Unexamined Patent Application Publication 2001-241693).
A desiccant rotor has a structure that is formed into a disk shape such that air can pass through in the direction of thickness thereof. A solid adsorbent material that has a porous inorganic compound as its primary constituent is provided on the surface of the desiccant rotor. A solid adhesive agent such as, for example, a silica gel, zeolite, a polymer adhesive agent, or the like, that is able to adsorb moisture, with pore diameters between about 0.1 and 20 nm, is used as the porous inorganic compound. Moreover, the desiccant rotor is driven by a motor, to rotate around a central axis, to continuously adsorb moisture from the air on the processing side and desorb moisture to the air on the regenerating side.
FIG. 17 shows a schematic of a conventional desiccant air-conditioning system that uses a desiccant rotor. In the figure, 100 is an air-conditioning device (a desiccant air conditioner) that generates air of a constant temperature with low humidity, and 200 is a dry area (an air-conditioned space) that receives the supply of constant-temperature/low-humidity air from the desiccant air conditioner 100. The desiccant air conditioner 100 is structured with a rotary moisture removing device 100A, as a moisture removing mechanism, and an air temperature adjusting device 100B, for adjusting the temperature of the air from which the moisture has been removed by the rotary moisture removing device 100A, disposed in a line.
The rotary moisture removing device 100A has a regenerating side fan 1 for producing an airflow on the regenerating side; a processing side fan 2 for producing an airflow on the processing side; a first desiccant rotor (a desiccant rotor for processing outside air) 3 that is disposed bridging the downstream side of a flow path L1 for the air on the regenerating side and the upstream side of a flow path L2 for the air on the processing side; a second desiccant rotor (a desiccant rotor for processing supply air) 4 that is disposed bridging the upstream side of the flow path L1 for the air on the regenerating side and the downstream side of the flow path L2 for the air on the processing side; a first cold water coil (a pre-cooling coil for processing the outside air) 5 for cooling the air on the processing side prior to moisture adsorption by the desiccant rotor 3 for processing the outside air; a second cold water coil (a pre-cooling coil for processing the supply air) 6 for cooling the air prior to adsorption of moisture by the desiccant rotor 4 for processing the supply air; a first hot water coil 7 for heating the air on the regenerating side prior to moisture desorption by the desiccant rotor 3 for processing the outside air; and a second hot water coil 7 for heating the air on the regenerating side prior to moisture desorption by the desiccant rotor 4 for processing the supply air. The air temperature adjusting device 100B comprises a cold water coil 9 and a hot water coil 10. The cold water coil 9 and the hot water coil 10 are disposed lined up in the flow path L2 for the air on the processing side that is sent from the rotary moisture removing device 100A to the dry area 200.
Note that M1 is a motor for rotating the desiccant rotor 3 for processing the outside air; M2 is a motor for rotating the desiccant rotor 4 for processing the supply air; S1 is a temperature sensor for measuring the exit temperature of the air that is cooled by the pre-cooling coil 5 for processing the outside air as the pre-cooling coil exit temperature ts1pv for processing the outside air; S2 is a temperature sensor for measuring the exit temperature of the air that is cooled by the pre-cooling coil 6 for processing the supply air, as the pre-cooling coil exit temperature ts2pv for processing the supply air; S3 is a temperature sensor for measuring the exit temperature of the air that is heated by the first hot water coil 7 as the hot water coil exit temperature tr1pv; S4 is a temperature sensor for measuring the exit temperature of the air that is heated by the second hot water coil 8, as the hot water coil exit temperature tr2pv; and S5 is a temperature sensor for measuring the temperature of the air (supply air) SA from the air temperature adjusting device 100B to the dry area 200, as the supply air temperature tspv.
The pre-cooling coil 5 for processing the outside air, in the rotary moisture removing device 100A, is provided with cold water CW through a cold water valve 11, and the pre-cooling coil 6 for processing the supply air is provided with cold water CW through a cold water valve 12. Moreover, a controller 13 is provided for the pre-cooling coil 5 for processing the outside air, and a controller 14 is provided for the pre-cooling coil 6 for processing the supply air. The controller 13 controls the degree of opening of the cold water valve 11 so that the pre-cooling coil exit temperature ts1pv for processing the outside air, measured by the temperature sensor S1, will go to a setting temperature (a pre-cooling coil exit temperature setting value for processing the outside air) ts1sp. The controller 14 controls the degree of opening of the cold water valve 12 so that the pre-cooling coil exit temperature ts2pv for processing the supply air, measured by the temperature sensor S2, will go to a setting temperature (a pre-cooling coil exit temperature setting value for processing the supply air) ts2sp. 
The first hot water coil 7 of the rotary moisture removing device 100A is supplied with hot water HW through a hot water valve 15, and the second hot water coil 8 is supplied with hot water HW through a hot water valve 16. Moreover, a controller 17 is provided for first hot water coil 7, and a controller 18 is provided for the second hot water coil 8. The controller 17 controls the degree of opening of the hot water valve 15 so that the hot water coil exit temperature tr1pv, measured by the temperature sensor S3, will go to a setting temperature (hot water coil exit temperature setting value) tr1sp. The controller 18 controls the degree of opening of the hot water valve 16 so that the hot water coil exit temperature tr2pv, measured by the temperature sensor S4, will go to a setting temperature (hot water coil exit temperature setting value) tr2sp. 
The cold water coil 9, in the air temperature adjusting device 100B, is provided with cold water CW through a cold water valve 19, and the hot water coil 10 is provided with hot water HW through a hot water valve 20. A controller 21 is provided for the cold water coil 9 and the hot water coil 10. The controller 21 controls the degree of opening of the cold water valve 19 and the hot water valve 20 so that the supply air temperature tspv, measured by the temperature sensor S5, will go to a setting temperature (a supply air temperature setting value) tssp.
In this desiccant air conditioning system, the outside air OA that is drawn in as air prior to processing is cooled, by the pre-cooling coil 5 for processing the outside air, to produce air at the setting temperature ts1sp, which is sent to the desiccant rotor 3 for processing the outside air. When this air passes through the desiccant rotor 3 for processing the outside air, moisture that is included in this air is adsorbed (moisture adsorption) by the solid adsorbing agent of the desiccant rotor 3 for processing the outside air. Given this, the air, after moisture adsorption by the desiccant rotor 3 for processing the outside air, is cooled again by the pre-cooling coil 6 for processing the supply air, to produce air of the setting temperature ts2sp, which is sent to the desiccant rotor 4 for processing of the supply air. When this air passes through the desiccant rotor 4 for processing the supply air, moisture that is included in this air is adsorbed (moisture adsorption) by the solid adsorbing agent of the desiccant rotor 4 for processing the supply air. Given this, the air after moisture adsorption by the desiccant rotor 4 for processing the supply air, that is, the air from which moisture has been removed by the rotary moisture removing device 100A, is sent to the air temperature adjusting device 100B, where the temperature is adjusted to produce supply air SA of the setting temperature tssp, which is supplied to the dry area 200.
On the other hand, on the regenerating side, outside air OA, as air on the regenerating side, is drawn in and sent to the hot water coil 8, and heated. This causes the temperature of the outside air OA to increase to the setting temperature tr2sp, reducing the relative humidity. At this time, the outside air OA is brought to a high temperature, in excess of 100° C. Given this, the outside air OA that is at the high temperature, wherein the relative humidity has been reduced, is sent, as air for regenerating, to the desiccant rotor 4 for processing the supply air.
The desiccant rotor 4 for processing the supply air rotates, so that the solid adsorbing agent that adsorbs the water content from the air on the processing side is heated when it faces the air for regenerating. Doing so causes the water content to be desorbed from the solid adsorbing agent, desorbing the moisture into the air for regenerating. The air for regenerating that has absorbed the water content from the solid adsorbing agent is again heated by the hot water coil 7 to become air at the setting temperature tr1sp, and is sent, as air for regenerating, to the desiccant rotor 3 for processing the outside air.
The desiccant rotor 3 for processing the outside air rotates, so that the solid adsorbing agent that adsorbs the water content from the air on the processing side is heated when it faces the air for regenerating. Doing so causes the water content to be desorbed from the solid adsorbing agent, desorbing the moisture into the air for regenerating. The air for regenerating that has absorbed the water content from the solid adsorbing agent is exhausted as exhaust air EA.
In this way, in the desiccant air conditioning system illustrated in FIG. 17, while the desiccant rotors 3 and 4 are rotated at a constant rotational speed and the speeds of rotation of the regenerating side fan 1 and the processing side fan 2 are held constant (the rated rotational speeds), the pre-cooling coil exit temperature setting value ts1sp for processing the outside air, the pre-cooling coil exit temperature setting value ts2sp for processing the supply air, the hot water coil exit temperature setting value tr1sp, and the hot water coil exit temperature setting value tr2sp are each held constant, and the adsorption of moisture from the air on the processing side and the desorption of moisture to the air on the regenerating side are performed continuously in the desiccant rotors 3 and 4, to continuously provide supply air SA (constant-temperature/low-humidity air) SA from the desiccant air conditioner 100 to the dry area 200.
However, in the desiccant air conditioning system set forth above, the volumes of the air to the regenerating side of the desiccant rotors 3 and 4 are set so as to be constant, based on the peak times for the amount of moisture adsorption on the processing side of the desiccant rotors 3 and 4, so as to be able to desorb the water content that is adsorbed at the peak times, and thus the energy consumption in the hot water coils 7 and 8 is terrible, and the operating costs are large.
That is, when the amount of water content included in the air on the processing side, drawn into the rotary moisture removing device 100A, is small, the amount of moisture that is adsorbed onto the solid adsorbing agents of the desiccant rotors 3 and 4 is small. Consequently, the water content that is desorbed from the solid adsorbing agent of the desiccant rotors 3 and 4 is small on the regenerating side as well. Nevertheless, the amount of air on the regenerating side that is supplied to the desiccant rotors 3 and 4 is a constant amount of air based on the peak times for the amount of moisture adsorption on the processing side. Because of this, the amount of air for regeneration that is supplied to the desiccant rotors 3 and 4 is greater than necessary, and, to that extent, energy is consumed wastefully in the hot water coils 7 and 8.
Given this, the present applicant conceived of adding an inverter INV1 to the regenerating side fan 1, as illustrated in FIG. 18, and detecting the dew point temperature of the supply air SA to the dry area 200 through a dew point temperature sensor 22, to apply, to a controlling device 23, the dew point temperature (the supply dew point temperature) tdpv of the supply air SA that is detected by the dew point temperature sensor 22, to control the rotational speed of the regenerating side fan 1 so that the supply air dew point temperature tdpv will be caused, by the controlling device 23, to go to a target dew point temperature tdsp. Doing this causes the amount of air for regeneration that is supplied to the desiccant rotors 3 and 4 (the regenerating air flow rate) to be adjusted so that the supply air dew point temperature tdpv will always be the target dew point temperature tdsp, making it possible to reduce the amount of energy consumed in the hot water coils 7 and 8.
For example, if the supply air dew point temperature tdpv were less than the target dew point temperature tdsp, then the rotational speed of the regenerating side fan 1 would be reduced, to reduce the regenerating air flow rate. When the regenerating air flow rate is reduced, then the temperatures of the regenerating air from the hot water coils 7 and 8 increase. In this case, control is performed so as to maintain the temperatures of the regenerating air at the setting temperatures tr1sp and tr2sp, and thus the amount of hot water HW supplied to the hot water coils 7 and 8 would be reduced, reducing the energy consumed by the hot water coils 7 and 8.
Note that while in FIG. 18 that which is controlled is the rotational speed of the regenerating side fan 1 (the regenerating air flow rate); however, one may also consider controlling instead the rotational speeds of the desiccant rotors 3 and 4, or controlling the exit temperatures of the air heated by the hot water coils 7 and 8. For example, in Japanese Unexamined Patent Application Publication 2003-262376, the humidity within the room is detected and the heating temperature on the regenerating side is controlled based on the humidity that is detected.
However, even though it is possible to reduce the energy consumption by constraining a control value for that which is being controlled in a system wherein the regenerating air flow rate is controlled in this way, or wherein the rotational speeds of the desiccant rotors are controlled in this way, or wherein the exit temperatures of the hot water coils are controlled in this way, it cannot be said that the reduction in energy consumption is adequate, and it is desirable to achieve even greater energy conservation.
The present invention is to solve such a problem, and the object thereof is to provide a desiccant air conditioning system, and operating method thereof, able to achieve further energy conservation through reducing energy consumed in the pre-cooling coil for processing supply air, while maintaining the target dew point temperature in the air-conditioned space.